onBWDone return value?????

I try for 10 hours, and find nothing in internet.

If I set return value of onBWDone, it wont get return value.

BW.fla

nc.client = new Clienta();

Clienta.as

public function onBWDone(... rest):String{
var bandwidthTotal:Number;
if (rest.length > 0)
{
if (rest.length > 0)
{
bandwidthTotal = rest[0];
textx = "Bandwith from server to client is: " + bandwidthTotal + " Kbps";
trace(textx);
return textx;
}
else
{
trace ("NOTHING");
return "NOTHING";
}

 

}
}

red text, that is problem and can not get value of bandwidthTotal.

how can I get this value of return

bandwidthTotal